Information storage systems are widely used in consumer and industrial products. In addition to conventional storage devices, optical information storage has been widely investigated for potentially low cost, high density storage. Moreover, optical storage can also be used as a component of spatial light modulators, optical switches and reconfigurable optical interconnects.
Optical storage generally relies on persistent effects of an optical medium. In this regard, persistent effects have been studied in wide bandgap semiconductors. For example, persistent photoconductivity has been observed in P and N-type Gallium Nitride, as described in publications entitled "Persistent Photoconductivity in n-Type GaN" to Beadie et al., Applied Physics Letters, Vol. 71, No. 8, 25 Aug. 1997, pp. 1092-1094 and "Deep Levels and Persistent Photoconductivity in GaN Thin Films"to Qiu et al., Applied Physics Letters, Vol. 70, No. 15, 14 Apr. 1997, pp. 1983-1985. Optical metastability in bulk Gallium Nitride single crystals have also been observed, as described in a publication by Shmagin et al., entitled "Optical Metastability in Bulk GaNSingle Crystals", to Shmagin et al., Applied Physics Letters, Vol. 71, No. 4, 28 Jul. 1997, pp. 455-457. Finally, optical memory effects have also been seen in Gallium Nitride epitaxial thin films that have distinct morphological features. See the publication entitled "Optical Memory Effect in GaN Epitaxial Films", to Joshkin et al., Applied Physics Letters, Vol. 71, p. 234 (1997).